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This queue is for tickets about the Image-JpegTran CPAN distribution.

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Id: 108482
Status: new
Priority: 0/
Queue: Image-JpegTran

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Owner: Nobody in particular
Requestors: marc [...] sketchfab.com
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Subject: Image alteration using jpegtran optimize
Date: Thu, 5 Nov 2015 10:32:20 +0100
To: bug-Image-JpegTran [...] rt.cpan.org
From: Marc Helbling <marc [...] sketchfab.com>
Hi jpegtran team, we are using jpegtran in production to losslessly improve file sizes. So far we are very happy. We have however encountered a case where the jpegtran optimization seems to partially alter an image. Sample data is available at https://gist.github.com/marchelbling/0c97ce5aac8f863783b4: * `Model_0.jpg`: original image file (md5sum: 2302771b6a5802de5319667f8b06f906) * `no_optimize.jpg`: result of `jpegtran -copy none -outfile optimize.jpg Model_0.jpg` (md5sum: 2302771b6a5802de5319667f8b06f906) * `optimize.jpg`: result of `jpegtran -optimize -copy none -outfile optimize.jpg Model_0.jpg` (md5sum: 9dcdd05b0f85323da99685bdf4d7b21c) The input image has no metadata so I can't tell where it comes from. The issue is in the "bottom" pixels of `optimize.jpg` which is blackish. Reading Model_0.jpg using OpenImageIO, then dumping it and running the optimization produces an unaltered image. Right now I don't have a fix for jpegtran and I'm checking if the optimization is changing any pixel from the original image. Thanks a lot for any help/advice. System information: Running in a docker container based on ubuntu:14.04.1 official image. # uname -a Linux cec7b9e76c60 3.11.0-26-generic #45~precise1-Ubuntu SMP Tue Jul 15 04:02:35 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux # perl -v This is perl 5, version 18, subversion 2 (v5.18.2) built for x86_64-linux-gnu-thread-multi # dpkg -s libjpeg-turbo-progs Package: libjpeg-turbo-progs Status: install ok installed Priority: optional Section: graphics Installed-Size: 182 Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com> Architecture: amd64 Source: libjpeg-turbo Version: 1.3.0-0ubuntu2 Replaces: libjpeg-progs (<< 8c-2ubuntu5) Provides: libjpeg-progs Depends: libc6 (>= 2.14), libjpeg8 (>= 8c) Description: Programs for manipulating JPEG files This package contains programs for manipulating JPEG files: cjpeg/djpeg: convert to/from the JPEG file format rdjpgcom/wrjpgcom: read/write comments in JPEG files jpegtran: lossless transformations of JPEG files tjbench: a simple JPEG benchmarking tool Homepage: http://libjpeg-turbo.virtualgl.org/


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